Trolley for mast arms



y 1934- A. M ILRATH TROLLEY FOR MAST ARMS Filed Nov. 5, 1931 2 Sheets-Sheet 1 May 15, 1934. A. MCILRATH 1,959,172

TROLLEY FOR MAST ARMS Filed Nov. 5, 1931 2 Sheets-Sheet 2 IN VEN TOR $4.1 ATTORNEYS Patented May 15, 1934 J UNITED STATES TROLLEY F01. MAST ARMS Arnold McIlrath, Pittsburgh, Pa, assignor to Hubbard and Company, a corporation of Pennsylvania Application November 5, 1931, Serial No. 573,194

6 Claims. (Cl. 105155) This invention relates to mast arms of the type which is used to support a lighting fixture in spaced relation to a pole or mast on which it is mounted, and more particularly, to improvements in the construction of the lighting fixture supporting trolley which is movable along the mast arm.

Arms of this type usually include a boom shaped so as to form an enclosed trackway and are provided with a trolley which is movable along the trackway and which is adapted to support a lighting fixture. So that the trolley may be readily moved to the outer end of the boom when in use and inwardly toward the pole when it is necessary to clean or renew the lighting fixture or any part thereof so that such operation may be conveniently performed from the pole end of the boom a chain and sprocket mechanism is usually provided. The ends of the driving chain are secured to the trolley and the chain extends around a sprocket situated at the pole end of the boom across the top of the trolley and around an idle roller in the outer end of the boom. In such construction the chain frequently becomes wedged in between the wheels or rollers and the frame of the trolley and before the trolley can be moved it is necessary for a man to crawl out on the boom and loosen the sprocket chain.

It is an object of this invention to provide a trolley for a mast arm which is so constructed that it is impossible for the chain to wedge between the wheels and frame of the trolley.

Another object of this invention is to provide a trolley for a mast arm having novel means for protecting the driving mechanism.

A further object is to construct a mast arm trolley having few and simple parts which are rugged in construction, positive in operation which will be cheap to manufacture and simple to install.

These and other objects which will be apparent to those skilled in this particular art are attained by means of this invention, one embodiment of which is described in the followingv specification and illustrated in the accompanying drawings, wherein:

Figure 1 is a view in side elevation of a mast arm having a trolley therein constructed in accordance with my invention;

Fig. 2 is a vertical longitudinal section of the mast arm;

Fig. 3 is a horizontal longitudinal section of the inner end of the mast arm;

Fig. 4 is a view in perspective of my improved trolley;

Fig. 5 is a view in side elevation of the trolley having the rollers removed, and

Fig. 6 is a view in section taken on line VI-VI oi Figure 2, and having the chain removed for convenience of illustration.

Referring to the drawings in detail, 10 designates a sheet metal boom having an inverted U-shaped cross section the ends 11 of which are curved inwardly so as to form an enclosed trackway 12. A trolley 13 is supported within the boom and is adapted to be driven or moved along the enclosed trackway from one end of the boom to the other. The driving mechanism includes a sprocket chain 14, one end of which is secured to the end of the trolley 13 which is nearest the boom supporting pole. From this end of the trolley the chain 14 passes rearwardly adjacent the trackway 12 to a sprocket wheel 15 which is secured to a rotatable shaft 16 near the inner end of the boom. The chain passes around the sprocket wheel 15 and outwardly along the upper edge of the boom, across the top of the trolley 13 to an idler roller 17 on the outer end of the bottom and thence back to the trolley 13 to which it is secured.

The sprocket wheel 15 may be rotated in either direction through the medium of a crank handle 18 which is pivoted to a projecting end of a sprocket shaft 16. Obviously rotation of the sprocket-wheel 15 will move the trolley along the enclosed trackway through the driving chain 14. The shaft 16 extends through slots 19 and 20 formed in opposite sides of the boom and is adjustable in the slots lengthwise of the boom through the medium of a substantially U-shaped bracket 21 the ends of which rotatably receive the shaft on opposite sides of the sprocket wheel 15.

In order to prevent the chain from sagging below the hollow boom so that the entire mechanism will be enclosed within the bottom and 93 protected from the elements, the bracket 21 has a. slot in the base thereof through which the hooked end 22 of a tension rod 23 extends. The rear end of the tension rod 23 is screw threaded and extends through an opening 24 in a plate 25 160 secured in the rear end of the boom. A wing nut 26 or similar device is threaded onto the outer end of the tension rod and. seats against the plate 25. Obviously, the rotation of the nut in either direction moves the bracket 21 length- 1 65 wise of the boom and increases or decreases the tension on the chain 14 depending on the direction in which the nut is rotated.

When the trolley 13 is in its desired position along the length of the boom it is locked in place by a latch securing the crank arm 18 against movement. The means for locking the crank arm against movement includes a hooked member 27 which is secured to the bracket 21 and has a hooked end depending below the bottom of the boom 10. When the handle 18 is placed in the end of the member 27, a latch 28 pivoted to the member 27 looks the handle therein. An opening 29 is provided in the latch 28 through which a padlock or similar means may be ex-" tended for preventing tampering supporting fixture.

My improved trolley 13 comprises a frame member 30 which may be formed by casting or, in any other suitable manner, having a vertically extending leg 31 which projects downwardly between the ends 11 of the boom 10 when the trolley is positioned therein and supports a lighting fixture. The portion of the frame within the boom has open rings 32 and 33 formed therein on each side of the fixture supporting leg 31 in which the axles connecting wheels or rollers 34 and *35, respectively, are journaled. The openings inthe rings 32 and 33 are slightly less than the diameter of the axles and the ends of the rings are yieldable and permit the axles to be forced into the rings. This spring action or yieldability of the ends of the open rings effectively retains the rollers in the frame member. The wheels 34 and 35 are mounted in the trackways 12 when the trolley is positioned in the boom 10. In order that the trolley may be readily moved along the boom without the chain being wedged between the frame and the wheels thereof, recesses 36 and 3'? are formed in the ends of the frame 30 on each side of the leg 31 for receiving the ends of the chain 14 and guards 38 are formed on the frame over the wheels. The guards 38 extend upwardly and outwardly from the top of the frame, covering the wheels and forming a groove therebetween for receiving the chain 14. The end of the chain 14 may be secured in the recesses 36 and 37 with any suitable means such as cotter pins threaded through the chain and extending through openings in the frame on each side of the recesses. The top of the frame 30 is substantially the same width as the distance between the wheels and the guards 38 effectually prevent the chain 14 from engagement therewith.

It is readily apparent that I have designed a trolley for a mast arm in which it is impossible for the chain to become entangled with the wheels regardless of the slack in the chain.

It is understood that while I have described with the light one embodiment of my invention, I am not limited to the specific details thereof, and certain changes, modifications, and substitutions may be made therein without departing from my invention or the scope of the appended claims.

. What I claim as new and desire to secure by Letters Patent is:

1. A trolley for mast arms comprising a T- shaped frame, having the ends of the horizontal portion thereof, provided with open rings and being flared upwardly and outwardly above said rings to' form a chain receiving groove therebetween.

2. A trolley for mast arms comprising a pair of spaced roller members, a frame supported by said roller members and having portions thereof flared outwardly and upwardly to cover said roller members and to form a chain receiving recess therebetween.

3. A trolley for a mast arm comprising a cast frame'member having an open ring formed in each end thereof, an axle disposed in. each of said open rings, rollers on the ends of said axles and guards integral with said frame extending upwardly and outwardly therefrom for covering the rollers and forming a chain receiving groove on the top of said frame member.

4. A trolley for a mast arm comprising a pair of spaced axle connected rollers, a T-shaped frame having an open ring on the underside of the cross bar portion at each end thereof forming a bearing for the axles of said rollers, and means on the upper side of said frame forming a chain receiving channel therealong.

5. A trolley for mast arms comprising a T- shaped frame having an open ring formed on the underside of the cross bar portion at each end thereof, an axle disposed in each of said open rings and rollers on the ends of said axles, the portion of said cross bar above said open rings being projected upwardly and outwardly to cover the tops of said rollers and form a longitudinally extending chain receiving groove therebetween.

6. A trolley fora mast arm comprising a frame having a fixture supporting member depending from the center thereof, an axle connected roller supporting said frame on each side of said member being in the form of an open ring to form bearings for the axles of said rollers and the portion of said frame above said open rings being flared outwardly and upwardly to coverthe tops of said rollers and form a chain receiving groove therebetween.

ARNOLD McILRATH. 

